The present invention relates to an aqueous liquid for forming soap bubbles, and more particularly, to an aqueous liquid for playing to form soap bubbles, which is prepared by using edible raw materials, has a high safety and is suitable for children""s recreations or amusements.
With change in social environments, indoor games such as personal computer games have extensively prevailed as children""s recreations. However, since such indoor recreations keep children in their rooms all day long, outdoor recreations have been recently recommended to protect children from being adversely influenced by these indoor games. Bubble blowing play is one of most popular outdoor recreations for children. Meanwhile, as a solution for forming bubbles, there have been used a soapy water, etc., which are capable of readily forming soap bubbles upon blowing. When the soapy water is blown upon playing, it is likely that children erroneously suck the soapy water in their mouths. However, soap has a bitter taste and, therefore, is unfavorable as a raw material of the aqueous liquid for forming soap bubbles. Further, there arises a problem that children, especially infants, tend to erroneously drink in or swallow the soapy water upon playing.
As a result of the present inventors"" earnest studies for solving the above-mentioned problems, it has been found that an aqueous liquid for forming soap bubbles, containing a specific ester of fatty acid with polyhydric alcohol, which is capable of forming soap bubbles upon blowing, has substantially no bitter taste and can show a high safety upon erroneously drinking. The present invention has been attained on the basis of the finding.
It is an object of the present invention to provide an aqueous liquid for forming soap bubbles showing a high safety even when the aqueous liquid is erroneously drunk in or swallowed, aid therefore, being suited for children""s recreations or plays.
To accomplish the aim, in a first aspect of the present invention, there is provided an aqueous liquid for forming soap bubbles, which comprises, as an emulsifier, an ester of a fatty acid having 8 to 14 carbon atoms with a polyhydric alcohol having not less than four hydroxyl groups,
the percentage of esterified hydroxyl groups of the polyhydric alcohol being 1 to 25% based on total hydroxyl groups of the polyhydric alcohol.
In a second aspect of the present invention, there is provided a method of preparing an aqueous liquid for forming soap bubbles, which contains, as an emulsifier, an ester of a fatty acid having 8 to 14 carbon atoms with a polyhydric alcohol having not less than four hydroxyl groups, wherein the percentage of esterified hydroxyl groups of said polyhydric alcohol based on total hydroxyl groups thereof is 1 to 25% based on total hydroxyl groups of the polyhydric alcohol, for using as an aqueous liquid for forming soap bubbles.
In a third aspect of the present invention, there is provided a method of forming soap bubbles using an aqueous liquid comprising, as an emulsifier, an ester of a fatty acid having 8 to 14 carbon atoms with a polyhydric alcohol having not less than four hydroxyl groups, wherein the percentage of esterified hydroxyl groups of said polyhydric alcohol based on total hydroxyl groups thereof is 1 to 25%, for preparing an aqueous liquid for forming soap bubbles.
The present invention will be described in detail below.
In an aqueous liquid for forming soap bubbles (hereinafter referred to merely as xe2x80x9csoap-bubbling aqueous liquidxe2x80x9d) according to the present invention, in order to obtain an excellent bubble-forming property, there can be used an ester of a fatty acid having 8 to 14 carbon atoms with a polyhydric alcohol having not less than four hydroxyl groups, in which the percentage of esterified hydroxyl groups of the polyhydric alcohol is 1 to 25% based on total hydroxyl groups of the polyhydric alcohol. When the number of carbon atoms of the fatty acid is less than 8 or more than 14, the obtained soap-bubbling aqueous liquid cannot exhibit a sufficient bubble-forming property.
Typical examples of the fatty acid moiety may include caprylic acid, capric acid, lauric acid, myristic acid or the like. Among them, fatty acids composed mainly of myristic acid are preferred from the viewpoint of taste. The content of myristic acid in the preferred fatty acids is preferably not less than 30% by weight, more preferably 40 to 100% by weight based on the weight of the fatty acids.
Typical examples of the polyhydric alcohol moiety may include sugars or sugar alcohols such as sucrose, sorbitol, glucose, fructose, maltose, raffinose, lactose, xylose, mannitol, erythritol or maltitol, sugar alcohol derivatives such as polyoxyethylene sorbitan, glycerols such as polyglycerol, or the like. Among them, sucrose and polyglycerol are preferred. Further, as the polyglycerols, those having a polymerization degree of not less than 4 are more preferred.
The percentage of esterified hydroxyl groups of the polyhydric alcohol is usually 1 to 25%, preferably 5 to 22% based on total hydroxyl group of the polyhydric alcohol. When the percentage of esterified hydroxyl groups of the polyhydric alcohol is more than 25%, the obtained soap-bubbling aqueous liquid is deteriorated in bubble-forming property. Such a percentage of esterified hydroxyl groups of the polyhydric alcohol may be determined according to the following method.
That is, for example, in the case of sucrose fatty ester, there can be adopted a method of separating the ester into individual components which are different in percentage of esterified hydroxyl groups of the polyhydric alcohol from each other, by gel permeation chromatography (GPC), and calculating the percentage of esterified hydroxyl groups from peak areas of the respective components. In the gel permeation chromatography, xe2x80x9cTSK-gel G2500HXLxe2x80x9d produced by TOSO CO., LTD. may be used as a separation column, and tetrahydrofuran may be used as an eluent. Further, in the case of polyglycerol fatty ester, there may be adopted a method of calculating the percentage of esterified hydroxyl groups from the ratio of polyglycerol to fatty acid charged into a reactor upon reaction and the amount of residual polyglycerol after the reaction. In this case, the separation of the residual polyglycerol may be conducted, for example, by a liquid-liquid extraction method using an aqueous solution containing isobutyl alcohol and sodium sulfate.
The fatty acid esters used in the present invention are preferably selected from the emulsifer being approved as food additives.
The soap-bubbling aqueous liquid according to the present invention can be produced by dissolving the above-mentioned fatty ester as an emulsifier in water. The amount of the fatty ester used is usually 0.1 to 10% by weight, preferably 0.5 to 5% by weight based on the weight of the soap-bubbling aqueous liquid.
The soap-bubbling aqueous liquid according to the present invention may usually contain a thickener to impart an appropriate viscosity thereto. Especially, thickeners used as foods or food additives are more preferred. Typical examples of the thickeners may include thickened polysaccharides. Specific examples of the preferred thickeners may include microbe-yielded viscous materials such as xanthan gum, gellan gum, pullulan or curdlan; plant seed viscous materials (mucilage derived from seed) such as guar gum (guaran), locust bean gum, tamarind seed gum or tara gum; sea weed extracts such as carrageenan or agar; vegetable resin viscous materials (mucilage derived from vegetable resin) such as gum arabic, tragacanth gum or karaya gum; plant fruit viscous materials (mucilage derived from plant fruits) such as pectin or arabinogalactan; celluloses such as methyl cellulose, hydroxymethyl cellulose or hydroxypropyl cellulose; starches such as starch or modified starch; or the like. In addition, as the thickeners, there can also be used animal proteins such as gelatin, albumin or casein, and plant proteins such as soybean protein or wheat protein. These thickeners can be used singly or in the form of a mixture of any two or more thereof.
The amount of the thickener used is varied depending upon kind and aimed viscosity thereof. In the case of thickened polysaccharides, the amount of the thickener used therefor is usually 0.001 to 5% by weight, preferably 0.01 Lo 0.2% by weight based on the weight of the soap-bubbling aqueous liquid.
Further, the soap-bubbling aqueous liquid according to the present invention may contain various other additives preferably which are approved as foods or food additives, if required.
For example, the use of an ionic emulsifier such as an organic acid monoglycerol ester or the like as the other additives can suitably enhance the solubility of the polyhydric alcohol fatty ester. The amount of such an ionic emulsifier used is usually 0.1 to 20% by weight, preferably 1 to 10% by weight based on the weight of the polyhydric alcohol fatty ester. These emulsifiers can be used singly or a mixture thereof.
Also, the addition of sugars to the soap-bubbling aqueous liquid can impart a sweetness, can improve in its favorableness, and is useful to stabilize properties of the soap-bubbling aqueous liquid. As such sweetenings, there can be used saccharides or sugar alcohols. Specific examples of the saccharides may include sucrose, glucose, fructose, maltose, maltotriose, raffinose, lactose, xylose, galactose or the like. In addition, specific examples of the sugar alcohols may include mannitol, sorbitol, glycerol, erythritol, maltitol, lactitol or the like. The amount of the sweetenings added is varied depending upon the intended product, and is usually 0.1 to 20% by weight, preferably 0.1 to 10% by weight based on the weight of the soap-bubbling aqueous liquid. Further, in addition to the above-mentioned additives, the soap-bubbling aqueous liquid may appropriately contain perfumes, colorants, souring agents, preservatives, alcohols or the like.
The soap-bubbling aqueous liquid according to the present invention is less bitter taste when sucked into mouth and suitable for bubble blowing play. Further, the soap-bubbling aqueous liquid is safe even when erroneously drunk in or swallowed and capable of forming soap bubbles by blowing air thereinto.